1. Field of the Invention
The present invention relates in general to engine analysis and more particularly to apparatus and methods for indicating certain performance characteristics of machines having one or more cylinders with pistons reciprocating therein, such as internal combustion engines, compressors, a machine combining both of these, etc.
2. Description of the Prior Art
In the gas transmission industry, it is necessary to compress and pressurize the natural gas prior to distribution of the gas over the pipeline network. Rather large engine-driven compressors are used to perform this compression function and the engines to rotate the compressors use fuel. A very real need exists to be able to measure the indicated horsepower of a reciprocating power cylinder or compressor cylinder in order to optimize the amount of power that is being generated and used and optimize the amount of fuel which is being used to generate that power and generally account for the energy that is being produced and used in, for instance, the gas transmission industry. The indicated horsepower of an internal combustion engine or a reciprocating piston type of compressor, can be determined by multiplying the area of the pressure-volume (P-V) card obtained from each cylinder by the crankshaft speed. The area of the P-V card can be expressed mathematically by the following equation: A= pdv, where p is the instantaneous pressure in the cylinder and dv is the first derivative of the instantaneous volume of the cylinder. Usually a signal representative of the instantaneous pressure in the cylinder can be obtained without too much difficulty. An accurate representation of the instantaneous volume of the cylinder is not easily obtained because the volume in the cylinder above the piston does not change at a constant rate.
The invention as claimed is intended to provide a solution for various prior art deficiencies by providing a means to accurately and easily measure the indicated horsepower and also provides means for displaying other parameters, including crankshaft angle and piston position related events, on the engine or compressor which are of interest in carrying out preventative maintenance measures and schedules.